Method of forming a rectangular heat duct

ABSTRACT

A machine designed to continuously progress a pair of elongated flat sheets of metal longitudinally through a plurality of cooperative dies which progressively in sequential steps gradually shape the two sheets into a duct having a rectangular cross-sectional configuration. The machine utilizes cooperative rotary dies to shape and form the duct in a continuous operation to a length equal to that of the sheets so that rectangular ducts of any desired length can be produced in an automatic operation by merely inserting into the machine a pre-prepared roll comprised of a pair of sheets of metal of the desired length, the sheets entering the machine at one end and leaving the same at the other end in the form of a continuous rectangular duct.

I United States Patent 1 1 1 3,722,443

Anderson et al. 1 Mar. 27, 1973 METHOD OF FORMING A 3,505,719 4/1970OMalley et a1 ..29/200 B RECTANGULAR HEAT DUCT 3,407,640 10/1968 Lipp..72/181 [75] Inventors: Leroy E. Anderson; Gerald J. FOREIGN PATENTS ORAPPLICATIONS Munn, both of Detroit Lakes, Minn.

723,908 2/1955 Great Britain ..72/52 [73] Assignee: ManufacturersSystems, Inc., 385,642 11/1923 Germany ..113/54 Detroit Lakes, Minn.Primary Examiner-Richard J. Herbst [22] Fled: 1971 AttorneyEverett J.Schroeder et a1. [21] Appl. No.: 205,843

[57] ABSTRACT Related US. Application Data A machine designed tocontinuously progress a pan of DlVlSlOl'l of Set. NO. l9, Pat. NO.elongated flat heets of metal through a 3,636,903 plurality ofcooperative dies which progressively in sequential steps gradually shapethe two sheets into a [52] US. Cl ..113/54 duct having a rectangularcross,sectional configura [51] Int. Cl. ..B2ld 39/02 tion The machineutilizes cooperative rotary dies to [58] Field of Search ..l13/54, 55;29/157, 200 B, Shape and f the duct in a continuous operation to 29/514;72/51, 52, 181; 219/59; 228/15 a length equal to that of the sheets sothat rectangular ducts of any desired length can be produced in an au-References Cimd tomatic operation by merely inserting into the machine apre-prepared roll comprised of a pair of UNITED STATES PATENTS sheets ofmetal of the desired length, the sheets enter- 489,498 1/ 1893 Pruden..72/52 ing the machine at one end and leaving the same at 2,502,0123/1950 Kinkead ...228/ 15 the other end in the form of a continuousrectangular 2,682,850 7/1954 Close ..72/51 duct, 3,250,077 5/1966 Ede...l l3/54 3,457,629 7/1969 Janecek ..L ..29/514 22 Claims, 32 DrawingFigures PATENTEUHARZYIQYS $722 443 SHEET OZUF 1O 5m 5 mmm E 2 M: W M w 9m 4 \w T\\ Wm i. 2; m l ing g W a r a 5/ a 4 a 5 3 4 J a A a 7 4 5 a 8x3. .3 M n Q F 4 F 4 METHOD OF FORMING A RECTANGULAR IIEAT DUCT Thisinvention relates to heating ducts. More particularly, it relates tomachines for forming elongated metal ducts having a rectangularcross-sectional configuration. This application is a divisionalapplication of our copending application, Ser. No. 12,663, filed Feb.19, 1970, and entitled RECTANGULAR-DUCT FORM- ING MACHINE," now US. Pat.No. 3,636,903.

There is a vast demand today for elongated metal ducts which aregenerally rectangular in cross-sectional configuration. This isparticularly true in the heating industry and especially true withrespect to the manufacture of mobile homes. The manufacture ofrectangular heating ducts has posed a substantial problem for a longtime, particularly where the duct is to be quite extensive in length, aswill be realized from the description hereinafter of the method by meansof which such 'ducts have been formed.

The conventional manner of producing rectangular heating ducts hasheretofore involved first the selection of a flat sheet of metal of thedesired length of the heating duct, provided such length was not toogreat to make proper handling of the sheet possible. Where relativelylong lengths of heating duct were required, such ducts were made inshorter sections and then subsequently secured together. This wasparticularly true where the ducts had to be transported from thelocation of manufacture to the location of installation. To manufacturethe heating ducts, the flat sheet was formed with a male lock at oneedge and a female lock at the opposite side edge, and thereafter theelongated sheet was bent simultaneously throughout its length to impartthe rectangular shape and to bring the male and female edges together,preparatory to moving them into mating relation. The final step involvedthe insertion of the male into the female lock to lock the same to eachother. Great difficulty has been experienced in assembling these locks,the main problem being the fact that the male or female edge isfrequently bent inadvertently during the efforts involved in shaping theflat sheet into the desired rectangular shape, and, as aconsequence,great difficulty is experienced in bringing the two edges into propermating relation. The length of such sections is obviously limitedbecause of these difficulties. Since a duct of any appreciable lengthmust be assembled section by section if it is to be manufactured by themethods heretofore known, a great expenditure of time, effort, andmaterials is involved in the manufacture of ducts having appreciablelength by these methods.

It is a general object of our invention to provide a machine constructedand arranged to continuously frame and adapted to receive and.progressively shape along their length a pair of elongated flat sheetsof metal, in sequential steps, into a duct having a rectangularcross-sectional configuration.

Another object is to provide a machine constructed and arranged toreceive and continuously progress a pair of elongated flat sheets ofmetal therethrough, the sheets being formed by and leaving the machinecontinuously in the form of a duct having a rectangular cross-sectionalconfiguration, the forming of the duct being accomplished through aseries of partial progressive bending steps accomplished sequentiallythrough the use of rotary dies at points spaced along the length of thesheets while they are passing through the machine.

Another object is to provide a novel machine constructed and arranged toenable a duct manufacturer to rapidly and efficiently produce elongatedducts of rectangular cross-sectional configuration of any predeterminedlength by merely feeding into the machine a pair of flat sheets of metalpre-cut to the same predetermined length.

Another object is to provide a novel machine constructed and arranged tomanufacture rectangular ducts of any predetermined length at a verysubstantial saving in time, labor and costs.

Another object is to provide a. novel machine constructed and arrangedto manufacture rectangular ducts automatically at great saving, themachine itself being compact, automatic in operation, inexpensive tomanufacture, trouble-free in operation, and inexpensive and simple tooperate and maintain.

Another object is to provide a portable machine which permits users ofrectangular ducts such as mobile home manufacturers to manufacture theirduct needs in single sections of desired length, whatever they may be,attheir operations base, to thereby eliminate the need for transportingpreformed tubular sections sheets of metal in an automatic operationwhich produces an end product having improved quality and performancecharacteristics.

Another object is to provide a machine which automatically constructsrectangular ducts from pairs of flat sheets of metal and which obviateSthe heretofore need of forming such ducts by bending the material fromwhich the duct is to be made simultaneously throughout its length andwhich obviates the great difficulties heretofore encountered inassembling the male and female locks utilized in the known conventionalmanufacturing methods of ducts so shaped.

These and other objects and advantages of our invention will more fullyappear from the following description, made in connection with theaccompanying drawings, wherein like reference characters refer to thesame or similar parts throughout the several views, and in which:

FIG. 1 is a diagrammatic plan view of the preferred form of ourinvention with stations indicated thereon and without the seamflattening mechanism being included;

FIG. 2 is a diagrammatic side elevational view of the embodiment shownin FIG. 1;

FIG. 3 is a diagrammatic vertical sectional view taken through stationNo. 1 of the embodiment shown in FIG. It;

FIG. 4 is a diagrammatic vertical sectional view taken through theembodiment shown in FIG. 1, at station No. 2, and illustrating how theoutermore lateral portions of the two sheets are shaped preliminarilytoward becoming cooperative seam elements;

FIG. 5 is a diagrammatic vertical sectional view taken through theembodiment shown in FIG. 1, at station No. 3, and illustrating themanner in which the innermore lateral portions of the two sheets arecrimped preliminarily to bending each sheet into oppositely facingchannel members and the outermore lateral portions are shaped finallyinto seam elements;

FIG. 6 is a diagrammatic vertical sectional view taken through theembodiment shown in FIG. 1, at station No. 4, and illustrating themanner in which the lateral portions are guided inwardly at' the beadline about the fixed die and into the adjacent and following rotary diemembers;

FIG. 7 is a diagrammatic vertical sectional view taken through theembodiment shown in FIG. 1, at station No. 5, and illustrating themanner in which the rotary dies cooperate with the fixed die at the beadline and present the outermore lateral portions of the lower sheettoward the corresponding portions of the upper sheet;

FIG. 8 is a diagrammatic vertical sectional view taken through theembodiment of FIG. 1, at station No. 6, and illustrating the mannerin'which the guide rollers bend the lateral portions of the sheetsfurther inwardly about the bead line and present the lower seam elementsto the upper seam elements at an inwardly disposed position tofacilitate subsequent inter-engagement;

FIG. 9 is a diagrammatic vertical sectional view taken through theembodiment shown in FIG. 1, at station No. 7, and illustrating themanner in which the cooperative rotary members complete the bend at thebead lines to 90 and commence closing the same;

FIG. 10 is a diagrammatic vertical sectional view of the embodimentshown in FIG. 1, taken at station No. 8, and illustrating thecooperative camming members closing the seam by camming the overlyingseam lip of the upper sheet into parallel and underlying relation to theedge portions of the lower sheet;

FIG. 11 is a diagrammatic vertical sectional view taken through theembodiment shown in FIG. 1, at station No. 9, and illustrating thefinishing operation in which the seam is compressed and buttoned topositively lock the seam elements together;

FIG. 12 is a diagrammatic perspective view illustrating how the two flatsheets are taken from a single roll by the embodiment shown in FIG. 1and progressively formed into a duct having a rectangularcross-sectional configuration, the respective station numbers beingindicated thereon at the point at which the two sheets take the shapesindicated thereat;

FIG. 13 is a diagrammatic side elevational view of the controls for thefeeding mechanism and initial forming rollers at station No. 1;

FIG. 14 is a diagrammatic side elevational view showing the springloading provided for the upper set and lower set of rollers of thefeeding mechanism and initial forming dies of station No. 1;

FIG. 15 is a diagrammatic detailed perspective view of the seam cammingmembers shown in FIG. 10;

FIG. 16 is a detailed diagrammatic view, shown on an enlarged scale, ofthe buttoning operation of the rotary dies shown in FIG. 11;

FIG. 17 is a diagrammatic vertical sectional view of a rectangular-ductforming machine constructed similarly to the embodiment shown in FIGS.1-16, with the exception that its dies are constructed and arranged toform the seams at the corners of the duct rather than at a pointintermediate the corners, the view being taken at station No. 1 with therollers in separated position;

FIG. 18 is a diagrammatic vertical sectional view of the embodimentidentified in the description of FIG. 17 and taken at station No. 2thereof;

FIG. 19 is a diagrammatic vertical sectional view taken at station No. 3of the embodiment identified in the description of FIG. 17 andillustrating the forming of the lip at the extreme lateral portions ofthe wider sheet and the initial break at the innermore lateral portionsthereof;

FIG. 20 is a diagrammatic vertical sectional view taken at station No. 4of the embodiment identified in the description of FIG. 17 andillustrating the rollers or helpers which guide the roller sheet fromstation No. 3 into the succeeding dies of station No. 5 and initiate thebending of the lateral portions upwardly at the break line incooperation with the fixed die;

FIG. 21 is a diagrammatic vertical sectional view taken at station No. 5of the embodiment identified in the description of FIG. 17 andillustrating the cooperation between the rotary dies and the fixed diesto bend the lateral portions sharply upwardly;

FIG. 22 is a diagrammatic vertical sectional view taken at station No. 6of the embodiment identified in the description of FIG. 17 andillustrating the use of the roller guides to further bend the lateralportions upwardly and inwardly tO a point adjacent the lateral portionsof the upper sheet;

' FIG. 23 is a diagrammatic vertical sectional view taken at station No.7 of the embodiment identified in the description of FIG. 17 andillustrating the cooperation of rotary diesto form the sealing lip atthe lateral edge of the upper sheet and the bringing of the lateralportions of the lower sheet to a truly vertical position inwardly of thelip;

FIG. 24 is a diagrammatic vertical sectional view taken at station No. 8of the embodiment identified in the description of FIG. 17 andillustrating the cooperation of rotarY dies to bring the sealing lip toa vertically extending position at the end of the sealing element of thelower sheet and in position to be sealed;

FIG. 25 is a diagrammatic Vertical sectional view taken at station No. 9of the embodiment identified in the description of FIG. 17 andillustrating the cooperation of rotary dies to bring the sealing lip ofthe upper sheet inwardly and around and below the sealing element of thelower sheet;

FIG. 26 is a diagrammatic vertical sectional view taken at station No.10 in the embodiment identified in the description of FIG. 17 andillustrating fixed cams which bring the 'lip into sealing positionbeneath and against the sealing element at the edge of the lower sheet;

FIG. 27 is a diagrammatic vertical sectional view of the embodimentidentified in the description of FIG. 17 and illustrating the manner inwhich the buttoning dies form the buttons in the seam to lock thesealing elements to each other;

FIG. 28 is a diagrammatic vertical sectional view on an enlarged scaletaken through the channel guides which support the upper metal sheetduring the forma tion of the embodiment identified in the description ofFIG. 17;

FIG. 29 is a diagrammatic fragmentary side elevational view of a dualcradle mechanism which may be carried by the frame to support twoseparate rolls of sheet metal in feeding relation to either of the ductforming mechanismsin lieu of a single composite roll comprised of a pairof such sheets;

FIG. 30 is a diagrammatic vertical sectional view taken through theembodiment of FIG. 1 and showing at station No. structure which may beadded t0 flatten the seam against the side wall of the duct in the eventsuch is desired;

FIG. 31 is a diagrammatic vertical sectional view taken through stationNo. 11, which may be added to the combined structure shown in FIG. 1 andFIG. 30, lllustrating the final step by means of which the seam isflattened against the side wall of the duct;

FIG. 32 is a diagrammatic side elevational view showing the means bywhich the rotary dies illustrated in FIGS. 30 and 31 may be driven bythe same drive mechanisms as that shown in FIG. 2.

The preferred embodiment, as shown in FIGS. l-l6, include a movableframe F which is adapted to be moved to a desired location through theuse of rollers 1 at the lower end of a plurality of vertically extendingsupports 2. A cradle 3 rotatably supports a single roll 4 of a pair 5and 6 of metal sheets. These sheets are arranged in superimposedcontiguous relation with each other and rolled into a single roll sothat their convolutions are concentric. The upper sheet 5 is slightlywider than the lower sheet 6 and, as can be best seen in FIG.

3, they enter the feeding and initial crimping mechanism, indicatedgenerally by the numeral 7, in-

vertically spaced relation as they unwind from the roll The frame F iselongated and has a pair of vertically extending side members 8 whichare transversely spaced from each other and carry support brackets 9,which in turn carry elongated transversely spaced fixed inner diemembers 10. These fixed inner die members 10, as shown in FIGS. 69, arecomprised of elongated flat metal plates which protrude forwardly beyondthe brackets 9 a substantial distance, which can be seen by reference toFIG. I.

If desired, a pair of separate rolls l1 and 12 (see FIG. 29) of sheetmetal may be utilized in lieu of the single composite roll 4. In thatevent, the rolls l1 and 12 are rotatably supported similarly to the roll4 upon a composite cradle 13, which utilizes saddles 14 and 15 torotatably support the shafts on which the rolls are carried. When dualrolls 11 and 12 are utilized, the upper sheet 15 is fed into the machinein vertically spaced relation to the lower sheet 16, as shown.

FIG. 1 shows the preferred embodiment of our duct forming machine withthe various stations to be hereinafter referred to indicated thereonalong the length of the machine. It will be noted that station No. l ispositioned immediately adjacent the roll 4. This station No. l, which isshown in greater detail in FIG. 3, utilizes a feeding and initialcrimping mechanism 7 which includes an upper set of rotary die members17 and 18, the upper one of which is rotatably mounted so as to becapable of vertical movement relative to the lower rotary die 18. Topermit such movement, each end of the die member 17 is rotatably mountedin a spring loaded bearing structure 19 at each of its ends,

the details of which are clearly shown in FIG. 14. Thus,

. cally slidable mounting block 21 and the shaft of the roller 17downwardly toward engagement with the lower die 18, which is mounted forrotation about a fixed axis upon the frame F.

The upper roller 17 has tapered metal end portions 22 and a majorintermediate portion 23, which is formed ofa firm but resilientmaterial. The lower metal roller 18 has enlarged end portionscharacterized by a bevelled surface 24, which is complementary to thebevelled surface 22 of the upper roller 17, and a flat angular surface25 which extends parallel to and bears against the cylindrical endportion of the roller 17, so that when the two rollers 17 and 18 arebrought together these surfaces will function as cooperative rotarydies.

The outersurface of the roller 18 is characterized by a plurality ofangular radially outwardly extending circumferential beads 26, which arespaced longitudinally of the roller 18 and a pair of longitudinally andoutwardly extending ribs 27. These ribs 7 extend parallel to the axis ofthe roller 18 and are carried at its circumferential surface and aredisposed at opposite sides of the roller.

The lower set of cooperating rotary dies are adapted to receive andprogress the lower sheet of metal through the machine and they are thecounterpart of the rollers 17 and 18. The lower roller 28 of this set isconstructed similarly to the roller 17 and is similarly mounted forrotation and vertical movement in similar movable bearings, except thatthey are inverted so as to constantly urge the roller 28 upwardly towardthe cooperative rotary die 29 which, like the die 18, is mounted forrotation about a fixed axis on the frame F.

The rotary die 29 has angular beads 30 similar to the beads 26 andlongitudinally extending ribs 31 similar to the ribs 27. It also has abevelled surface 32 similar to the surface 24, but, as shown, it has nosurface comparable to the angular die surface 25. The relatively narrowlower sheet 6 obviates any need for such a surface. The rotary grippingmembers 17 and 28 are adjusted relative to the rotary die members 18 and29 through the use of a control system indicated generally by the letterC, which will be described in greater detail hereinafter.

When the two sheets of metal from the roll 4 have been inserted betweenthe members 17, 18 and 28, 29, they will be progressed thereby throughthe remainder of the machine, since they are each power driven, as willbe hereinafter described. The longitudinal ribs 27 and 31 and theangular beads 26 and 30 impart or form ribs on the surface of the flatsheets and provide added rigidity thereto. The cooperative bevelledsurfaces 22 and 24 form a 30 bend of the lateral or edge portions of thesheet 5, and the angular surface 25 shapes the extreme edge portions soas to extend parallel to the main body of the sheet, as will be readilyappreciated by reference to FIG. 3. This is the initial step inprogressively forming the outermore lateral portions of the upper sheetinto a sealing element which will ultimately become a portion of theseam. At the same time, the rotary die 29 imparts a bend to the narrowerlower sheet 6, at its extreme edge, of a 30 angle, there being no edgeportion left extending parallel to the main body of the sheet 6, sincethe sheet is narrower. Thus the extreme edge portion of the sheet 6 isbent downwardly and away from the sheet 5, just as the lateral portionsof the sheet are bent away from the sheet 6.

From station No. 1, the two sheets 5 and 6 move to station No. 2, atwhich location it enters the second stage of the duct forming operation.At this location, as shown in FIG. 4, there is positioned a second pairof vertically spaced sets of cooperating rotary dies to impart furthershaping of the lateral portions of the sheets 5 and 6, so that theseaming elements will extend at a 60 angle relative to the main body ofthe sheets. At this station there is located an upper set of rotarydies, identified by the numerals 33 and 34. Each of these dies consistsof a shaft rotatably mounted in the frame F and carrying a rotary diemember at each of its ends and shaped so as to be complementary andcooperate with the die member of the other. Thus the rotary die 33 hasat each of its ends a die member having a flat annular surface 35 and abevelled 60 surface 26 and an enlarged cylindrical surface 37. The die34 has at each of its ends a rotary die having an annular surface 38 anda 60 bevelled surface 39 and an enlarged cylindrical surface 40. Asclearly shown in FIG. 4, the surface 35 cooperates with the surface 38and the surface 36 cooperates with the surface 39 to impart a 60 angleto the sealing element, and the surface 37 cooperates with thecylindrical surface 40 to maintain the very edge portion or lip 41parallel to the main body of the sheet 5.

The lower set of rotary dies, indicated generally by the numerals 42 and43, are similarly mounted and arranged, the die 42 being constructedidentically with the die 34. The lower rotary die 43 is constructedidentically with the upper rotary die 33, and they cooperate to impart a60 angle to the sealing element 44 at the very edge of the lower sheet6.

From station No. 2, which is shown in FIG. 4, the sheets 5 and 6 areprogressed to station No. 3, at which location there is disposed anothergroup of vertically spaced sets of driven rotary dies, mounted forrotation upon the frame F and spaced transversely thereof. As shown inFIG. 5, the upper set is comprised ofa pair of cooperating rotary diesidentified generally by the numerals 45 and 46. These dies consist ofelongated shafts rotatably mounted upon the frame F and carrying at eachof its ends a cooperating rotary die member constructed and arranged toimpart additional shaping to the lateral portions of the sheets 5 and 6,preparatory to forming a rectangular duct therefrom. The rotary die 45has a die member at each of its ends, which has an annular surface 47separated from an outwardly tapering surface 48 by an annular groove 49.At the larger end of this die is an essentially flat surface 50, whichextends essentially normal to the shaft upon which these die members aremounted, and a reduced annular surface 51 is provided outwardly thereof.

The die 46 carries at each of its ends a cooperative rotary die membercharacterized by an annular surface 52 separated from an outwardlydiminishing frustoconical surface 53 by an annular rib 54, which ispositioned to extend into the groove 49 as the die members rotate. Thisdie member is further characterized bY a surface 55 which extendsessentially normal to the shaft of the die 46 and is positioned slightlyoutwardly of the surface 50 so as to cooperate therewith to impart aangle to the seam element 56. It is further characterized by an enlargedannular surface 57, which cooperates with the cylindrical surface 51 tocause the lip 41 to extend essentially normally to the sealing element56.

The lower set of rotary dies, identiFied by the numerals 58 and 59, aresimilarly constructed and arranged to shape the lower sheet 6. Therotary die 58 is constructed identically with the rotary die 46, and therotary die 59 is constructed identically to the rotary die 45, and theycooperate in a similar manner to impart the same shape to the lateralportions of the sheet 6, except, of course, that the extreme edgeportion, or sealing element 44, carries no lip element corresponding tothe lip element 41 because of its narrower width.

From station No. 3, which is shown in FIG. 5, the sheets move to stationNo. 4, at which they encounter the structure shown in FIG. 6. At stationNo. 4, the sheets reach a helper station at which they are guidedinwardly by a plurality of rotatably mounted rollers 60, eaehof which iscarried by a spindle or shaft 61 and is supported upon one of transversemembers 62 or 63 as shown in FIG. 6. It is at this station that thesheets 5 and 6 first encounter the fixed die member 10, which arepositioned so as to be disposed just inwardly of the break lines 64,which were imparted to the two sheets by the cooperative action of theannular ribs 54 and grooves 49 at station No. 3, as shown in FIG. 5. Itwill be noted that the rollers 60 are positioned so as to engage thelateral portions of the sheets 5 and 6 just inwardly of the sealingelement. These rollers 60 are not driven, but are free to rotate on theshaft 61, which in turn are adjustably mounted on the transverse members62 and 63 through the use of sleeves as shown. These rollers 60 guidethe lateral portions of the sheets 5 and 6 inwardly toward each other soas to progressively break the sheets at the break line 64 and guide theminto the rotary dies at station No. 5, which are shown in FIG. 7.

FIG. 7 shows a plurality of driven rotary dies cooperating with thefixed dies 10. A power driven upper shaft 65 is rotatably mounted uponthe frame F to extend transversely thereof and carries at each of itsend portions a rotary die member 66 having a cylindrical surface 67 anda 53 outwardly bevelled surface 68. Each of these rotary die members 66are positioned so that the cylindrical surface 67 bears upon the uppersheet 5 just inwardly of outer surface of the fixed die member 10 andthe bevelled surface is disposed just outwardly thereof so as to bringthe lateral portions of the sheet member 5 inwardly 53 from the plane ofthe sheet. The shaft 65 also carries at each end a diskshaped guidingmember 69, which rotates with the shaft and extends into the angleformed by the sealing element 56 so as to guide the outermore lateralportions of the sheet inwardly toward the sheet 6, as shown in FIG. 7.

A lower and similarly mounted shaft 70 carried identically constructedguide members 69 and a pair of rotary die members 71, which areconstructed and positioned similar to the rotary die member 66 exceptthat the angle of the bevel 72 is such as to impart a 57 angle to thelateral portions of the sheet 6 and thus move the sealing element 44inwardly at each side to an extent farther and ahead of the sealingelement 56 of the sheet 5. This arrangement is utilized in ordertoinsure that upon further movement of the lateral portions of the twosheets inwardly the sealing elements will m ate Properly.

From station No. 5, as shown in FIG. 7, the sheets and 6 move onwardlyto station No. 6, which is shown in FIG. 8. Here again, the sheetsencounter a helper station in the form of rollers 73, each of which isrotatably mounted for free rotation about a spindle 74 that is carriedby a sleeve 75 upon a transverse member such as 76 or 77. These rollers73 guide the lateral portions of the sheets 5 and 6 further inwardly asthey bend further at the break lines 64. It will be noted that therollers 73, which are carried by the lower transverse member 77, arepositioned inwardly slightly farther than those carried by the uppermember 76 so that the sealing element 44 is disposed somewhat inwardlyof the sealing element 56 and the lip 41 at each side of the machine.Note that the two sheets 5 and 6 have been gradually and progressivelyformed in sequential steps into two oppositely facing channel memberswhich are essentially U-shaped in cross-sectional configuration. Asthese sheets continue to progress through the machine, even furtherbending takes place until a truly rectangular configuration is obtained.The effect of the rollers 73 is felt by the material of the sheets 5 and6 which is disposed thereahead so that the sheets are properly guidedinto the mechanism at station No. 7, which is shown in FIG. 9.

At station No. 7 thereis provided a plurality of rotary die membersconstructed and arranged to close the rectangular configuration .andcommence to close the lip 41 around the sealing elements 44 so 'as tohold the latter between it and the sealing element 56. Carried by theframe Fat opposite sides of the fixed dies 10' and cooperating therewithis a pair of rotary die members which are identical in construction andidentified generally by the numeral 78. Each of these rotary die members78 has a cylindrical compressing surface 79 and a slightly bevelledinner end surface 80. The latter gradually bends the lateral portions ofthe sheet 5 inwardly to a 90 angle against the fixed die and at the sametime the cylindrical surface 79 brings the sealing element 56 and thelip41 downwardly and around the relatively inwardly disposed sealingelement 44. A pair of rotary die membersindicated generally by thenumeral 81 is also carried by the frame F in position to cooperate withthe rollers 78 and toward that end they are constructed to provide abevelled camming surface 82, which engages the lip 41 and brings itinwardly to an angulated position relative to the sealing element 56 andsomewhat around and below the sealing element 44 of the sheet 6. Thusthe construction shown completes the 90 bend at the side of the duct andcommences the closing of the seam member which ultimately consists ofthe two sealing elements 44 and 56 held in sealed position by thesealing element 41, as will be hereinafter described. It will be notedthat the two rotary die members 81 are. positioned at opposite sides ofthe fixed die members 10 and have similar bevelled inner ends whichcomplete the 90 bend of the sheet 6 at the break line 64 in addition tocommencing the cloSing of the seam.

From position 7 as shown in FIG. 9, the sheets 5 and 6 move to stationNo. 8, at which they encounter the structure shown in FIG. 10. At thisstation there is provided at each of the sides of the now rectangularconfiguration additional camming structure constructed and arranged tocomplete the formation of the seam. As shown in FIG. 10, mounted uponthe frame F outwardly of the fixed dies 5, and in position to receivetherein the seam elements 44 and 56 and the lip 41, is a pair of cammingmembers 83 and 84. These camming members 83 and 84 are fixed andvertically spaced from each other a distance essentially equal to thecombined thickness of the elements 41, 44 and 56. The end portions ofthe camming members 83 and 84 which face toward the direction from whichthe sheets 5 and 6 move are somewhat flared as shown in the detailedview of FIG. 14 to facilitate entrance of 'these elements thereinto. Asthe sheets 5 and 6 are drawn past station No. 8, the seam which is nowcomprised of the seam elements 44 and 56 and the lip 41 is completed,the lip 41 being brought into flattened position around and below thesealing element 44 of the lower sheet 6. Elements 83 and 84 are providedat each side of the duct so that as the sheets pass thereby the seam iscompleted to the configuration shown in FIG. 10.

As the now rectangular configuration comprised of the sheets 5 and 6leave station No. 8 as shown in FIG. 10, it proceeds to station No. 9,which is shown in FIG. 11. At this station the seam at each side of theduct, which consists of the elements 41, 44 and 56 in flattenedcondition, passes through one of a pair of vertically spaced rotary diemembers 8 5 and 86, one each of which is disposed at each side of theduct. Each of the rotary die members 85 is characterized by acylindrical surface 87, which bears against the outer surface of thesealing element 56 and a pair of recesses 88 which are oppositelydisposed within said cylindrical surface. A

bevelled end surface 89 is also provided to facilitate movement of therectangular duct thereby. Each of the rotary die members 86 ischaracterized by a cylindrical surface 90 which bears against theunderside of the sealing lip 41 and compresses the latter to flatten theseam and compress it. Each rotary die member has a pair of outwardlyextending buttons 91 which are positioned so as to pass directlyopposite the recesses 88 as they rotate, and thus impart a lockingbutton 92 at spaced locations approximately 3 inches apart along theseam to the metal of the elements 41, 44 and 56, which make up the seam.This button 92 positively locks the elements which make up the seam toeach other and precludes separation during subsequent handling of theduct. An enlarged detailed view of the button being formed is shown inFIG. 16'.

FIG. 12 shows a diagrammatic perspective view which illustrates themanner in which the individual sheets of the roll 4 gradually movetherefrom through the machine and assume in sequential steps the shapewhich is illustrated at the locations identifiedthereon by numeralscorresponding to the stations hereinbefore described. Thus it can beseen that the two flat sheets of metal 5 and 6 are progressivelyconverted from flat sheets into a duct having a rectangularcross-sectional configuration as these sheets are drawn through themachine, the duct entering the machine at one end in the form of twosheets and being discharged from the opposite end in the form of acontinuous rectangular duct which canbe constructed of any desiredpredetermined length merely by providing a roll having two such sheets 5and 6 of such desired length.

The feeding and initial crimping mechanism shown in FIG. 3 andidentified by the letter C is controlled through -a handle member 93which is fixedly connected to rotate with a transverse shaft 94 which isrotatably mounted and extends through the frame F. At each end of theshaft 94 there is a cam member 95, the details of which are shown inFIG. 13. These earns 95 are fixed to the shaft 94 and rotate therewith,and they have an irregular camming surface designed to control therelative movement of the members 17 and 28 toward and away from therotary die members 18 and 29. This isaccomplished through the use ofrollers or cam followers 96, which are carried at each end of themembers 17 and 28. Reference to FIG. 13 will disclose the irregularcamming surface of the earns 95.

The lever 93 and cam 95 are positioned in FIG. 1 so as to present thecamming surfaces having the maximum radius to the cam followers 96. Thisposition is identified as position No. 1 and, since the camming surfaces97 and 98 having the largest radius engage the cam followers 96 in thisposition, the upper roll 17 and the lower roll 28 will be positioned inopen position and in nonengaging relation to the rolls 18 and 29. Whilein this position the forward end of the lower sheet of metal 6 isinserted between the rolls 28 and 29 and the lever member 93 and thecams 95 are rotated about the shaft 94 to position No. 2, which is atthe camming surfaces identified by the numerals 99 and 100. It will benoted that the distance from the center of shaft 94 to the cammingsurface 99 is essentially equal to the" distance between that shaft andthe camming surface 97 at position No. 1 and hence the upper roll 17will remain in open position. on the other. hand, the distance from thecenter of shaft 94 to the camming surface 100 is substantially less thanthat between that shaft and the camming surface 98 at position No. 1 andhence the roll 28 will be moved by the springs, 20 into engagement ofthe forward end of the lower sheet 6 to grip the same in cooperationwith the roll 29.

Once the sheet 6 has been gripped between the rolls 28 and 29, the lever93 and cams 95 may be rotated further until the camming surfacesidentified by the numerals 101, 102 bear against the cam followers 96.This is known as the rest position in which the rolls 28 and 29 areclosed and the rolls 17 and 18 are also closed. This is true because itwill be seen that the distance from shaft 94 to camming surface 102 hasbeen reduced sufficiently so that roll 17 is permitted to lower and gripthe forward end 'ofthe upper sheet which is extended therebetweenmanually just prior'to movement of the lever to rest position, orposition No. 3. Further movement of the lever 93 sufficient to cause thecamming surfaces identified by the numerals 103 and 104 to engage thecam followerS 96 (position No. 4) leaves the rolls 17 and 18 and 28 and29 in position holding the sheets 5 and 6 in the same manner as inposition No. 3, but also closes an electrical switch which causes thedriving motor of the machine to be activated and rotate the rolls 17,18, 28 and 29 to cause the sheets 5 and 6 to be progressed through themachine.

In the event a flattened seam is desired, the frame F may be constructedof sufficient length to also carry the mechanisms shown in FIGS. 30-32,which will be described hereinafter. Description of the structure willbe made hereinafter subsequent to the description of the structuresshown in FIGS. 17-29 inclusive.

FIGS. 17-29 illustrate a similar machine to that shown in FIGS. 1-16,except that the dies are constructed and arranged to form the seams atthe corners of the rectangular duct rather than at the intermediateportions of the sides of the duct. The same cradles may be utilized asdesired, but the roll of metal will be comprised of sheets of differentwidths as is shown in FIGS. 17-28. The same type of feeding and initialcrimping mechanism may be utilized except that the rolls will beconstructed differently. Thus in FIG. 17, station No. 1 is shown whereinthe vertically movable roll is substantially shorter so as to conform tothe narrower widths of the upper metal sheet 111. The roll 110 isprovided with a resilient intermediate portion and metal end portionscomparable to the construction of the roll 17. The cooperating roll 112is constructed similarly to the roll 18, except that it, too, is shorterto conform to the narrower width of the upper sheet 111. The lowest roll113 is constructed similarly to roll 28, but it is longer in length toconform to the substantially greater width of the lower sheet 114. Theupper of the lower set of rolls 115 is constructed in the same manner asroll 29, except that it, too, has a substantially greater length toconform to the greater width of lower sheet 114. The rolls 110, 112,113, and 115 form the same functions of gripping and moving the sheetsforwardly as do the rolls shown in FIG. 3. The rolls 113 and 115 form .a30 angle of the edge portion of the sheet 114 in the same manner as therolls 28 and 29 function. Since the rolls 110 and 112, however, do nothave a bevelled the upper sheet 111 is to impart the transverse andiongitudinal ribs to the sheets to provide added rigidity in the samemanner that the beads 26 and ribs 27 function upon the sheet 5.

FIG. 18 shows station No. 2 of the modified form of the invention. Asthe sheets pass through station No. I, as shown in FIG. 17, they enterthe structure shown in FIG. 18 for further modification corresponding tothat which takes place in station No. 2 of the preferred embodiment.Thus, the rolls 116 and 117 correspond to rolls 42 and 43, and similarlyimpart a 60 angulation to the seal element 118 at each of the lateraledges of the sheet 114. The sheet 111 enters a pair of guiding channels119 and 120 which are supported by the frame F and extend longitudinallythereof at the central position shown. No modification of sheet 111takes place at station No. 2, and the only modification to sheet 114 isto impart a 60 angulation to the sealing element 118 and progress thesheet forwardly to station No. 3, which is shown in FIG. 19.

At station No. 3, the upper sheet 111 continues to ride within thechannel members 119 and 120, and no modification thereof is accomplishedat this station. The frame F carries at this station, however, a pair oftransverse shafts 121 and 122 which are power-driven and carrycooperative rotary die members. At each end of the shaft 121 there is arotary die having a cylindrical surface 123 which is reduced to abevelled surface 124 and tapers gradually thereto as at 125. Each ofthese rotary die members cooperate with another rotary die member suchas 126 that is carried by the lower shaft 122. These rotary dies 126have a somewhat bevelled end surface 127 which cooperate with thebevelled surface 125 to move the sealing element 118 to extend normal tothe immediately adjacent lateral portion of the sheet 114. The surfaces124 and 128 cooperate to hold the material immediately adjacent thesealing element 118 firmly.

Disposed inwardly of the rotary dies carried at the ends of the shafts121 and 122 are two pairs of cooperating dies which provide the initialbreak to the sheet 114 at break lines 129 and 130 which eventuallybecome the corners of the duct. The shaft 121 carries a pair ofidentical rotary dies 131, each of which is characterized by an annularcentrally disposed rib 132, and the adjacent surfaces of which slopeaway therefrom to a diminished radius, as clearly shown in FIG. 19.Cooperating with each of these dies 131 and carried by the shaft 122 inposition to form the break lines 129 and 130 is a pair of rotary diesindicated by the numeral 133. Each of these dies is characterized by anannular groove 134, which is centrally located intermediate the ends ofthe die and by an adjacent tapering surface which increases in radiusfrom the groove toward the outer end of the shaft and is indicated bythe numeral 135. As shown, these rotary dies cooperate to provide theinitial shaping of the sheet 114 toward a U- shaped construction adaptedto be closed eventually by the sheet 111.

As the sheets llland 114 leave station No. 3, they proceed towardstation No. 4, which is shown in FIG. 20. Here again the upper sheet 111continues to be carried by the channel members 119 and 120 withoutmodification thereto. It will be noted, however, that the fixed diemembers are now disposed above the lower sheet 114 just inwardly of thebreak lines 129 and 130. At this station there is provided a transverseshaft 136 which rotatably mounts by means of sleeves 137 and spindles138, a pair of guiding rollers 139 which rotate freely on the spindles.These rollers 139 provide a function comparable to that provided by therollers 60 in station No. 4 of the first embodiment and, as will be seenby reference to FIG. 20, bring the lateral portion of the sheet 114upwardly and inwardly and guide the same into the dies at station No. 5,which is shown in FIG. 21.

At station No. 5 in FIG. 21, the upper sheet 111 is still carried in thechannel members 119 and 120 and remains unmodified. The frame F carriesa transverse shaft 140 which rotatably mounts a pair of rotary dies suchas indicated by the numeral 141. Each of these dies has an annularsurface 142 and an outwardly bevelled surface 143 and is positioned sothat the latter surface engages the lateral portions of the sheet 114and bends them upwardly approximately S7 off the plane of the sheet 114.It will be noted that each is positioned so that the annular surface 142is disposed immediately below the fixed die members 10 and the bevelledsurfaces 143 commence at the outer surface of these fixed die members.Also carried by the driven shaft and disposed outwardly of the rotarydies 141 is a pair of guiding disks or rollers indicated generally bythe numeral 144. These guiding rollers are bevelled to come to an edgeintermediate their axial ends and are shaped so as to engage andcomplement the edge portion of the sheet 114, the edge 145 of each ofthese rollers extending into the angle formed by the sealing element 118.

As the sheets leave station No. 5 which is shown in FIG. 21, they moveto station N0. 6 which is shown in FIG. 22. At this station the uppersheet 111 still remains unmodified and is carried by the channel members119 and 120. A transversely extending shaft 146 is carried by the frameF and mounts by means of a sleeve 147 and a spindle 148, a freelyrotatable roller 149 at each of the outer sides of the fixed die 10. Thespindles 148 extend upwardly and slightly outwardly and position therollers 149 so as to bring the lateral portions of the sheet 114inwardly toward the fixed die members 110. These guide rollers 149 bringthe lateral portions to extent approximately 75 from the plane of thesheet 114 and guide the sheet into the mechanism of station No.7, whichis shown in FIG. 23.

The channel members 119 and 120 terminate between stations No. 6 and No.7 and at station No. 7 sheet 111 is acted upon by a pair of rotary diesindicated generally by thenumeral 150. This pair of rotary dies 150 ismounted upon a powered transverse shaft 151, which is carried by theframe F. Each of the rotary die members 150 cooperates with anotherrotary die member indicated generally by the numeral 152, which ispositioned immediately therebelow and supported upon a shaft 153 whichlikewise is powered and supported by the frame F. Each of the rotarydies 150 has an annular die surface 154 which terminates just short ofthe lateral edge of the sheet 111 and merges with an outwardly flaringdie surface 155, as shown in FIG. 23. The lower dies 152 have an annularsurface 156which cooperates with the annular surface 154 and merges intoa diminishing die surface 157 which cooperates with the flaring diesurface to form the outer edge portion of the sheet 111 into anangulated lip 158. It will be noted that the break lines 129 and 130 arespaced a distance less than the width of the sheet 111 so that the lip158 is formed opposite the outer end of the sealing element 118 andextends downwardly thereby. It will also be noted that the inner ends ofthe rotary dies 152 are bevelled as at 159 to facilitate engagement andpassage of the lateral portions of the sheet 114 as the sheet movesthrough the machine. The rotary dies 152 function to move the lateralportions of the sheet 114 so that they extend normal to the centralportion of the sheet and are brought flush against the outer surface ofthe inner dies 10 to complete the rectangular configuration. They alsofunction to bring the sealing element 1 l8 inwardly so that it will bepositioned inwardly of the lip 158.

As the two sheets 111 and 114 move from station No. 7, as shown in FIG.23, they proceed to station No. 8, which is shown in FIG. 24. It is atthis station that the sealing lip 158 is brought to vertically extendingposition and normal to the sealing element 118. This is accomplishedthrough the use of a pair of rotary die members indicated generally bythe numeral 160, which are carried upon a transverse shaft 161 mountedfor rotation upon the frame F. This shaft 161 is powered to rotate thetwo dies 160 at their position directly above the sealing element 118and lip 158. Each of the dies 160 has an annular surface 162 and anadjacent radially extending surface 163 which extends outwardlytherefrom at a position just outwardly of the break at the inner end ofthe lip 158. It also has an adjacent bevelled surface 164 which guidesand cams the lip 158 into position where the surface 163 can force asharp break or bend at the base of the lip. Cooperatingwith each of therotary dies 160 is one of a second pair of rotary dies indicatedgenerally by the numeral 165. Each of these dies is carried upon a shaft166 which in turn is mounted upon the frame F and is likewise powerdriven as shown. Each of the dies 165 has an annular die surface 167which merges with a bevelled surface 168 that extends inwardly therefromand is adjacent to a radially extending die surface 169. The surface 169engages the inner surface of the lip 158 and the annular surface 167cooperates with the annular surface 162 while the bevelled surface 168guides the lateral portions of the sheet 114 inwardly. It is at thisstation that the sealing lip is brought to a 90 orientation and thesealing element 118 is brought snugly up against the undersurface of thesheet 111 immediately adjacent this lip preparatory to forming a seamtherewith.

As the rectangular configuration shown in FIG. 24 leaves station No. 8,it moves toward station No. 9 which is shown in FIG. 25. It is at thisstation that the lip 158 is brought inwardly to a partially sealingposition. This is accomplished by a pair of rotary dies indicatedgenerally by the numeral 170 and carried by a power-driven shaft 171which is rotatably mounted on the frame F. The two rotary dies 170 arepositioned just outwardly of the two fixed die members 10 and arecharacterized by an annular surface 172 which bears against the uppersurface of the. sheet 111 and cooperates with one of a pair of rotarydies indicated generally by the numeral 173. These rotary dies 173 arepositioned immediately below one of the dies 170 and are characterizedby a frusto-conical camming surface 174 which terminates with a radiallyextending surface 175. These dies are'mounted upon a shaft 176 whichlikewise is mounted upon the frame F. As these dies engage the lip 158,the end of the lip bears against the radial die surface 175 of the dieI73, and the outer surface of the lip 158 is cammed inwardly by thefrustoconical camming surface 175 in cooperation with the annularsurface 172 of the die 170. The inner end of the die 173 bears againstthe outer surface of the lateral portions of the sheet 114 which has nowbecome the side walls of the rectangular duct.

As the sheets leave station No. 9 which is shown in FIG. 25, they movetoward station No. 10, which is shown in FIG. 26. At station No. 10 theedge portions ofthe sheet 111 pass between a pair of camming members 177and 178 at each side of the rectangular duct.

These camming members are flared similarly to those shown in FIG. 15 andeach pair is supported upon the frame F by brackets such as indicated bythe numeral 179. The camming members 177 and 178 compress the lip 158around and upwardly against the underside of the sealing element 118 andcam these elements tightly against the underside of the portion of thesheet 111 which extends laterally beyond the side walls of the duct.This action is highly similar to that described with respect to thepreferred embodiment as is. accomplished by the structure shown in FIG.15.

As the duct leaves station No. 10 as shown in FIG. 26, it moves to thefinishing station shown in FIG. 27. At this finishing station there isprovided a transverse shaft 180 which is mounted upon the frame F forrotation and is powered. It carries a pair of rotary die membersindicated generally by the numeral 181 each of which is characterized byan annular surface 182 which has a pair of recesses 183 formed in itsouter surface. These rotary dies 181 cooperate with a pair of rotarydies mounted immediately therebelow and identified generally by thenumeral 184. These dies likewise have an annular surface 185 whichcooperate with the annular surface 182 to further compress the seamformed by the elements 118 and 158 and further carry a pair ofoppositely disposed outwardly extending nipples 186 which are adapted toextend into the recesses 183 and form a button in the elements 118, 158,and the portion of the sheet 111 that extends outwardly beyond the sidewalls of the duct. In this manner, each of these elements is positivelylocked to the other to prevent separation during handling of the duct.The construction of the button is similar to that shown in FIG. 16.

The detailed view of FIG. 28 merely shows the manner in which the sheet111 rides upon the channels 1 l9 and 120 as hereinbefore described.

FIGS. 30-32 are shown herein to disclose the manner in which the seam ofthe first embodiment may be flattened, if such is desired. It will bereadily appreciated that if it is desired to flatten the seam of thesecond embodiment, it may be accomplished in the same manner by merelymoving the rotary die elements upwardly in position to engage the seamsat the corners and cam them downwardly. As shown, the seam can beflattened by adding a station 10 immediately forwardly of station No. 9of the first embodiment, the mechanism being comprised of two pairs ofcooperating rotary dies mounted upon the frame F in position to engagethe seam, the upper two dies identified by the numeral 187 beingprovided with a frusto-conical die surface 188 which flares outwardlyand cooperates with a lower die indicated generally by the numeral 189which carries a frusto-conical cooperating die surface 190. Thecooperating surfaces 188 and 190 provide an initial bend to the seam sothat it extends downwardly at approximately a 45 angle.

From. station No. 10 as shown in FIG. 30 the duct moves to station No.11 as shown in FIG. 31 wherein the seam at each side of the duct engagesa flattening die that is mounted for rotation on the frame F. Theseflattening dies 191 are characterized by a flat end surface 192 and anadjacent bevelled surface 193 which together cooperate to engage andflatten the seam against the extension of the fixed inner die 10 asshown. The dies 188 and 190 and 191 can each be driven by a geararrangement such as is shown in FIG. 32 which may be incorporated in thedrive mechanism disclosed in FIG. 2.

FIG. 2 shows diagrammatically the gear train provided to drive thevarious rotary dies hereinbefore described so as to cause the metalsheets to be progressed through the various sequential stepshereinbefore described. A source of power (not shown) such as anelectric motor is connected in driving relation to a drive gear 195.This drive gear 195 is connected in driving relation to a second drivegear 196 which is rotatably mounted upon the frame F. A drive chain 197extends around the drive gear 196 in the manner shown to drive theinter-engaging assembly of gears at the front and rear end of the frameF. The location of the various stations has been indicated in FIG. 2 byidentifying the various driving gears with the numerals of the shafts orrotary die members which they drive. It is believed that theinterrelation of these gears and the operation of the driving train willbe readily appreciated by anyone familiar with chain drives.

From the above it can be readily seen that we have provided a novelmachine which utilizes a plurality of rotary dies in such a manner thata pair of flat metal sheets may be fed into one end of the machine and acompletely constructed rectangular duct can be taken from the oppositeend as a result of an entirely automatic operation. Since the machine ismovable, it can be readily taken to any location where it is desired toutilize same, and, in fact, can be positioned adjacent an assembly linein a mobile home manufacturing plant, for example, so as to produce anddischarge rectangular ducts of any desired length and feed them directlyinto the partially constructed home as they pass our machine in theproduction line. A rectangular duct of any length desired can beproduced without difficulty and at a very substantial saving in cost,time and material. Moreover, there are no length limitations, and allthat is required to produce a duct of a prescribed length is to providea pre-prepared roll of a pair of sheets of that length and feed theminto the machine.

It will, of course, be understood that various changes may be made inthe form, details, arrangement and proportions of the parts withoutdeparting from the scope of this invention which consists of the mattershown and described herein and set forth in the appended claims.

What is claimed is:

l. A method of forming a rectangular air duct in a single continuousoperation consisting in:

a. providing a pair of elongated flat metal sheets in spaced parallelrelation,

progressively crimping the inner lateral portions at each side of eachof said sheets longitudinally from one of its ends toward the otheralong a corner line to facilitate bending of the lateral portions ofeach of such sheets toward the corresponding lateral portions of theother,

. bending simultaneously the lateral portions of such sheets toward eachother progressively in increments along their lengths until the lateralportions of one of such sheets abuts the lateral portions of the otherthroughout their lengths and a rectangular configuration incross-section is thereby defined, and

d. progressively forming an interlocking seam in the abutting lateralportions of such sheets from a point adjacent one of their ends towardthe other to positively lock and maintain such sheets in a cooperativerectangular duct-defining relation.

. The method defined in claim 1, and

. progressively bending the outer lateral portions of said sheetslongitudinally along seam lines so as to cause said outer lateralportions to extend substantially normal to their adjacent inner lateralportions and parallel to and in abutting relation to each other when therectangular configuration has been defined, and

f. progressively bending the extreme lateral portions of one of saidsheets so as to extend away from and parallel to its supporting innerlateral portions preparatory to the formation of an interlocking seamtherefrom.

3. The method defined in claim 2, and finally bending said extremelateral portions of one of said sheets so as to extend around the outeredge of the extreme lateral portion of the other sheet and along theopposite side thereof in close abutting relation preparatory to theformation of an interlocking seam therein.

4. The method defined in claim 1 wherein forming said interlocking seamconsists in simultaneously deforming in a progressive manner along theirlengths the abutting lateral portions of said sheets while they are inabutting relation.

5. The method defined in claim 1 wherein forming said interlocking seamconsists in simultaneously deforming in a progressive manner along theirlengths the abutting lateral portions of said sheets at pointsspacedalong substantially the entire lengths of said abutting portionsto cause the deformations produced therein to lock such portions to eachother.

6. The method defined in claim 1 wherein each of the crimping andbending steps set forth therein is performed sequentially andprogressively upon such sheets from one of their ends toward and to theother end.

7. The method defined in claim 1 wherein each of said crimping, bending,and forming operations isperformed sequentially and progressively uponsuch sheets from one of their ends toward and to the other end.

8. The method defined in claim 1 wherein each of the crimping operationsset forth therein, isaccomplished by passing said sheets longitudinallythrough cooperative rotary crimping, members from one of their endstoward and to the other end.

9. The method defined in claim -1 wherein each of the bending operationsset forth therein is accomplished by passing said sheets longitudinallyfrom one of their ends toward and to the other end between cooperativerotary bending members.

10. The method defined in claim 1 wherein the seam forming operationsset forth therein are accomplished

1. A method of forming a rectangular air duct in a single continuousoperation consisting in: a. providing a pair of elongated flat metalsheets in spaced parallel relation, b. progressively crimping the innerlateral portions at each side of each of said sheets longitudinally fromone of its ends toward the other along a corner line to facilitatebending of the lateral portions of each of such sheets toward thecorresponding lateral portions of the other, c. bending simultaneouslythe lateral portions of such sheets toward each other progressively inincrements along their lengths until the lateral portions of one of suchsheets abuts the lateral portions of the other throughout their lengthsand a rectangular configuration in cross-section is thereby defined, andd. progressively forming an interlocking seam in the abutting lateralportions of such sheets from a point adjacent one of their ends towardthe other to positively lock and maintain such sheets in a cooperativerectangular duct-defining relation.
 2. The method defined in claim 1,and e. progressively bending the outer lateral portions of said sheetslongitudinally along seam lines so as to cause said outer lateralportions to extend substantially normal to their adjacent inner lateralportions and parallel to and in abutting relation to each other when therectangular configuration has been defined, and f. progressively bendingthe extreme lateral portions of one of said sheets so as to extend awayfrom and parallel to its supporting inner lateral portioNs preparatoryto the formation of an interlocking seam therefrom.
 3. The methoddefined in claim 2, and finally bending said extreme lateral portions ofone of said sheets so as to extend around the outer edge of the extremelateral portion of the other sheet and along the opposite side thereofin close abutting relation preparatory to the formation of aninterlocking seam therein.
 4. The method defined in claim 1 whereinforming said interlocking seam consists in simultaneously deforming in aprogressive manner along their lengths the abutting lateral portions ofsaid sheets while they are in abutting relation.
 5. The method definedin claim 1 wherein forming said interlocking seam consists insimultaneously deforming in a progressive manner along their lengths theabutting lateral portions of said sheets at points spaced alongsubstantially the entire lengths of said abutting portions to cause thedeformations produced therein to lock such portions to each other. 6.The method defined in claim 1 wherein each of the crimping and bendingsteps set forth therein is performed sequentially and progressively uponsuch sheets from one of their ends toward and to the other end.
 7. Themethod defined in claim 1 wherein each of said crimping, bending, andforming operations is performed sequentially and progressively upon suchsheets from one of their ends toward and to the other end.
 8. The methoddefined in claim 1 wherein each of the crimping operations set forththerein is accomplished by passing said sheets longitudinally throughcooperative rotary crimping members from one of their ends toward and tothe other end.
 9. The method defined in claim 1 wherein each of thebending operations set forth therein is accomplished by passing saidsheets longitudinally from one of their ends toward and to the other endbetween cooperative rotary bending members.
 10. The method defined inclaim 1 wherein the seam forming operations set forth therein areaccomplished by passing said sheets longitudinally from one of theirends toward and to the other end between cooperative rotary die members.11. The method defined in claim 1 wherein the crimping and bendingoperations set forth therein are accomplished by passing such sheetslongitudinally from one of their ends toward and to the other endbetween cooperative rotary members.
 12. The method defined in claim 1wherein the crimping, bending, and forming operations set forth thereinare accomplished by passing such sheets longitudinally from one of theirends toward and to the other end between cooperative rotary members. 13.A method of forming a duct having a rectangular cross section in asingle continuous operation consisting in: a. providing a pair ofelongated flat metal sheets in spaced parallel relation, b.progressively crimping a sharp corner line in the inner lateral portionof each of said sheets at each of its sides, c. progressively bendingthe lateral portions of each of said sheets at its corner lines towardeach other in increments along their lengths until the lateral portionsof one of said sheets extend adjacent to and along the lateral portionsof the other throughout their lengths and said sheets therebycooperatively define a rectangular configuration in cross section, andd. progressively securing such adjacent lateral portions of the one suchsheet to those of the other along the length of said sheets in order tomaintain said sheets in cooperative rectangular duct-defining relation.14. A method of forming a rectangular air duct in a single continuousoperation consisting in: a. providing a pair of elongated flat metalsheets in spaced parallel relation, b. progressively crimping the innerlateral portions of said sheets longitudinally from one of their ends tothe other along corner lines to facilitate bending of the lateralportions of such sheets toward each other, c. simultaneously bending thelateral portions of such sheets toward each other progresSively inincrements along their lengths until the lateral portions of one of suchsheets overlaps the lateral portions of the other throughout theirlengths and a rectangular configuration in cross section is therebydefined, and d. progressively forming an interlocking seam in theoverlapping lateral portions of such sheets from one of their ends tothe other to positively lock and maintain such sheets in a cooperativerectangular duct-defining relation.
 15. The method defined in claim 14,and e. progressively bending the outer lateral portions of said sheetslongitudinally along seam lines so as to cause said outer lateralportions to extend substantially normal to their adjacent inner lateralportions and parallel to and in abutting relation to each other when therectangular configuration has been defined, and f. progressively bendingthe extreme lateral portions of one of said sheets so as to extend awayfrom and parallel to its supporting inner lateral portions prior to theformation of an interlocking seal therefrom.
 16. The method defined inclaim 15, and finally bending said extreme lateral portions of one ofsaid sheets so as to extend around the outer edge of the extreme lateralportion of the other sheet and along the opposite side thereof in closeabutting relation prior to the formation of an interlocking seamtherein.
 17. The method defined in claim 14 wherein forming saidinterlocking seam consists in simultaneously deforming in a progressivemanner along their lengths the overlapping lateral portions of saidsheets while they are in abutting relation.
 18. The method defined inclaim 14 wherein forming said interlocking seam consists insimultaneously deforming in a progressive manner along their lengths theoverlapping lateral portions of said sheets at points spaced alongsubstantially the entire lengths of said overlapping portions to causethe deformations produced therein to lock such portions to each other.19. Method of forming a rectangular-duct in a single continuousoperation consisting in a. providing a pair of elongated flat metalsheets in spaced parallel relation, b. progressively movinglongitudinally the lateral portions of each said sheets at each of itssides through a rotary crimping die to form a pair of spaced sharpcorner lines therein extending substantially throughout the length ofsaid sheet, c. progressively moving the lateral portions of said sheetsagainst and past a series of bending rollers and thereby progressivelybending such lateral portions toward each other until the lateralportions of one of said sheets abuts the corresponding lateral portionsof the other throughout the length of said sheets to cooperativelydefine a rectangular configuration in cross section, and d.progressively securing such adjacent lateral portions of the one suchsheet to those of the other along the length of said sheets to maintainsuch sheets in cooperative rectangular-duct defining relation.
 20. Themethod defined in claim 1 wherein said bending operation includes thestep of progressively camming the lateral portions of such sheets towardeach other in increments along their lengths.
 21. The method defined inclaim 1 wherein said bending operation includes camming the lateralportions of such sheets toward each other progressively in incrementsalong their lengths until the lateral portions of one of such sheetsabuts the lateral portions of the other throughout their lengths and arectangular configuration in cross-section is thereby defined.
 22. Themethod defined in claim 1 wherein said bending operation includescamming the lateral portions of such sheets toward each otherprogressively in increments along their lengths, and e. progressivelybending the outer lateral portions of said sheets longitudinally alongseam lines so as to cause said outer lateral portions to extendsubstantially normal to their adjacent inner lateral portions andparallel to and in abutting reLation in part at least to each other whenthe rectangular configuration has been defined.